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Biomedical subjects

R J Stewart

Publications and source records attributed to R J Stewart.

At least 127 records · Page 7Linked to original sources
PubMed1979

A micro macrophage migration inhibition test for the detection of cellular immunity in vitro.

A simple, economical, macrophage migration inhibition assay enabling multiple tests to be performed using microculture plates has been developed. The system confers many advantages over the standard in vitro assay of macrophage migration inhibition factor. It requires only 5 X 10(5) macrophages for each assay, small volumes (100 microliter) of test factors are consumed, 96 tests in each culture plate are easily assessed microscopically and the technique is easily and reproducibly executed. An adherent monolayer of activated fresh mouse peritoneal exudate cells (PEC) is established in each microculture well. A 'starting line' is scored across the monolayer by the application of a trimmed razor blade and the cells are dislodged and aspirated from one side of the line. Test factors from cultures of stimulated lymphocytes were added to the 'wounded' monolayer and the migration of macrophages from test and control cultures was measured after staining. The cells across the line were counted after incubation. Miration was shown to be time and temperature dependent, markedly stimulated by colchicine and appeared to associate with tuberculin antigen (PPD) skin testing and lymphocyte transformation in human subjects.

Animals↗
PubMed1979

Cancer of the large bowel in a defined population: Canterbury, New Zealand, 1970--4.

A total of 1024 new cases of cancer of the large bowel occurred in Canterbury, New Zealand (population 400,796), in the 5 years 1970--4. Of these, 992 were diagnosed before death and are reviewed in this paper. The high incidence of this disease in New Zealanders of European origin is illustrated. A significant difference in site distribution of primary tumours between the sexes was found, with a female preponderance of cancer of the proximal colon gradually changing to a male preponderance of cancer of the rectum. In all, 61.5 per cent of the patients had lymph node metastases or advanced disease at the time of diagnosis or treatment. Largely as a consequence of this, only 65 per cent were able to have potentially curative treatment. The estimated crude 5-year survival rate of the whole group was 32.7 per cent (relative rate 42.8 per cent) and the crude 5-year survival rate after potentially curative surgery was 48.4 per cent (relative rate 62.4 per cent). The results are compared with those of other authors. They emphasize the generally unsatisfactory outcome of treatment.

Adult↗
PubMed1979

The accumulation and elimination of diflubenzuron by fish.

In summary, diflubenzuron is accumulated from water into fish tissues at levels up to 80 fold within 24 hr when fish are exposed to concentrations of 10 ppb. Within the concentration range of 1-10 ppb, the amount accumulated in a 24 hr exposure is proportional to concentration. After 24 to 48 hr exposure fish degrade and eliminate diflubenzuron and the excretory products are neither the parent compound nor p-chlorophenylurea. The amount of diflubenzuron remaining in fish tissues with time is dependent on the reduction of residue concentration in water; however, the potential for degradation and elimination is very great.

Animals↗
PubMed1979

The migration of fibroblasts into an in vitro wound.

A method for the study in vitro of fibroblast migration in wounds is described. This consists of producing standard fibroblast monolayers (derived from subcultures of explants of flank skin from young male rats) in microtitre plates, wounding the monolayer in a linear fashion with razor blade, removing the monolayer from one side of the linear wound and retaining the other side for migration studies. Preliminary results using the method are described which illustrate its reproducibility and ease of performance.

Animals↗
PubMed1977

Operative cholangiography in two hundred consecutive cholecystectomies.

The records of two hundred consecutive patients undergoing cholecystectomy for gallstones in the university department of surgery, Christchurch Hospital, were reviewed to evaluate the benefit and standard of operative cholangiography. The main benefit lay in the avoiding of unnecessary common bile duct exploration. Of the cholangiograms later reviewed by an independent radiologist, only 70 percent were considered satisfactory.

Cholangiography↗
PubMed1975

Skeletal-muscle growth and protein turnover.

Because of turnover, protein synthesis and breakdown can each be involved in the regulation of the growth of tissue protein. To investigate the regulation of skeletal-muscle-protein growth we measured rates of protein synthesis and breakdown in growing rats during development on a good diet, during development on a marginally low-protein diet and during rehabilitation on a good diet after a period of severe protein deficiency. Rates of protein synthesis were measured in vivo with a constant intravenous infusion of [14C]tyrosine. The growth rate of muscle protein was measured and the rate of breakdown calculated as breakdown rate=synthesis rate-growth rate. These measurements showed that during development on a good diet there was a fall with age in the rate of protein synthesis resulting from a fall in capacity (RNA concentration) and activity (synthesis rate per unit of RNA). There was a fall with age in the breakdown rate so that the rate was highest in the weaning rats, with a half-life of 3 days. There was a direct correlation between the fractional growth and breakdown rates. During rehabilitation on the good diet, rapid growth was also accompanied by high rates of protein breakdown. During growth on the inadequate diet protein synthesis rates were lesss than in controls, but growth occurred because of decreased rates of protein breakdown. This compression was not complete, however, since ultimate muscle size was only one-half that of controls. It is suggested that increased rates of protein breakdown are a necessary accompaniment to muscle growth and may result from the way in which myofibrils proliferate.

Aging↗
PubMed1975

Twelve generations of marginal protein deficiency.

1. Colonies of rats have been maintained for twleve generations on diets adequate (dietary protein energy: total metabolizable energy (NDp: E) 0-1) or marginally deficient in protein (NDp: E 0-068). 2. In the malnourished colony, the proportion of "small-for-gestational-age" offspring was ten times as high as amongst the well-nourished colony, growth was slow, sexual maturation delayed, especially in the females, and, when adult, both sexes were significantly lighter and shorter than adults of the well-nourished colony. Organs, other than the eye, weighed less than those of well-nourished "age" controls, but when expressed relative to body-weight, the brain, pituitary, thyroid, adrenals, testes, thymus and eyes were larger, the pancreas unchanged and the kidneys smaller than those of the well-nourished "age" controls. The relative weight of the liver showed little change, being slightly increased in the males and, like the ovaries, slightly reduced in the females. On a body-weight basis, the brains were about 50 percent heavier than normal, but in absolute terms were 5-5-5 percent lighter than those of the well-nourished animals, the cerebellum (10-5 percent lighter in males and 12-9 percent lighter in females) being more severely affected than the cerebrum (4 percent lighter). 3. The young malnourished rats showed increased exploratory activity, transient head tremors and an increased sensitivity to noises, the latter being long-lasting if not permanent. When adult, they showed marked differences in behaviour and learning patterns and it was difficult to attract and hold their attention. In situations demanding a choice the animals were very excited, emitted loud squeals and tried to escape from what was clearly a stressful situation. However, a casual examination of the malnourished adults revealed a rather small, badly groomed, excitable rat without gross abnormalities. 4. The findings are discussed in relation to changes found in malnourished human communities.

Age Factors↗